No oil at the cam/lifters

[zephead69]

OK, I am lost and so is my mechanic.

I took the Opel in the other day because it has been making a lot of noise ever since I had the motor rebuilt a few months ago. I haven't driven it much since then but I am finally able to give it the care it needs, so....

There is no oil getting to the top of the engine. The oil pressure at the sending unit is 50psi, but it seems to get lost after that. The bottom of the engine doesn't seem to be making any noise or having any problems, but there is no oil keeping the lifters up, or on the camshaft, or anywhere else it seems. I found what I think is a good diagram of the oil pathway in the engine and it looks as if there is supposed to be a stream of oil that is pumped onto the timing chain at the tensioner. Does any of this sound remotely familiar to anyone? I am at a loss right now.

[soybean]

Who rebuilt the engine? you or your mechanic? When you had the head off do you think it's possible that the branch in the timing case to nos1 camshaft bearing is blocked? or got some trash in it?
The "FSM says the cylinder head oil gallery delivers oil under pressure to all valve lifters..... Next paragraph says "An additionally drilled passage connects the valve lifter circular groove with circular groove of rocker arm stud from where the oil is directed upwards through a drilled passage to the rocker arm seat" I found this in the 73 FSM under 6A-5.
There are others here that have more internal engine knowledge than I that I'm sure will jump in to help, but It sounds like something is blocked to the head.
Jarrell

[duaneb]

Have you tried running the engine with the valve cover off? There is four little aluminum plugs in the top of the casting that encloses the cam. If one or more of those plugs are missing you will get no pressure to the lifters and oil will shoot out the hole if you try to start it. The plugs are aprox 3mm.
I hade one plug come out while driving, valves clattered BAD, and the engine would just barely run.

[jeff denton]

I'm with duaneb, if there was really NO oil getting up there you'd have worse problems... you're just not getting sufficient oil. There's quite a few oil plugs in the head, some big ones and some small ones, even one outside the head by the thermostat neck.
Pull the valve cover off, remove the spark plugs, ground the coil wire, and spin the engine over. Look for excessive oil flow on the top end, like a big leak somewhere.
All the oil to the head comes from a tiny passage in the block, up to the deck, through the head gasket, into the head. I'm not aware of anything squirting oil on the chain, purposely.
There are threads about this, some posts cover how all these plugs are modified so as not to fall out. Our favorite way is to drill and tap them and put pipe plugs in them.

[GTJIM]

1) Did you have the cam bearings replaced? If so check that the oil holes line up correctly.
2) Were the oil passages in the head and block thoroughly cleaned out - with carb cleaner and rifle bore brushes - then cleaned again ..... and again??
3) Did you replace the cam? Some cams have an oil groove around the front lobe - some don't. The ones that don't need heads with a groove around the inside of the front cam bearing bore in the head for the oil to get to the rest of the head.
4) Check that there IS actually an oil hole with a seal around in in the cylinder head gasket .... there should be!

Here is a pic of the oil circuits. Note: that the oil is fed up through the drillings in the front of the block into drilled passage ways in the head. This feeds the front cam bearing. Oil flows from there up around the grove in the front cam journal, along the main gallery in the head which the hydraulic cam followers ("valve lifters") are fed from, and down into the other cam bearings. The groove in the front cam journal is sometimes not a full circle as this is used to meter oil to the head - I think mechanical cams have a partial groove and some hydraulics a complete groove (anyone confirm this?)

[markandson]

I do believe that there is also an O-ring that goes between the block and the head that seals the oil passage so no leakage occurs.

[tekenaar]

Originally Posted by markandson I do believe that there is also an O-ring that goes between the block and the head that seals the oil passage so no leakage occurs.

The only "O" ring at the head gasket is to seal a coolant passage. In Jim's picture you'll see that the oil for the head goes up a drilled passage in the timing cover to just short of the top before entering a transfer passage in the block, then vertically into a drilled horizontal passage in the head which feeds a vertical bore to the bottom of the front cam bearing.

All early heads used cams with grooved front bearing races which allow the oil to be routed to the lifter galley and rear cam bearings. NOTE!!: When replacing cam bearings in early heads, it is critically important that the front cam bearing holes, one at 6 o'clock and one at 11 o'clock, be perfectly aligned with the head's front cam bearing holes so that lifter galley and rear cam bearings' oil flow is unrestricted!! This is very likely your problem!

Later heads (2.2 and 2.4) had a groove machined into the front cam bearing surface and routed lifter galley oil around the outside of the front cam bearing.

[RallyBob]

Originally Posted by GTJIM The groove in the front cam journal is sometimes not a full circle as this is used to meter oil to the head - I think mechanical cams have a partial groove and some hydraulics a complete groove (anyone confirm this?)

Correct Jim. Partial groove on the front cam journal for early engines with solid lifters, and a full groove on the hydraulic cams until about 1980 or so. At this point the cam design/oil passage design changed again as Otto mentioned. On these newer heads the front cam journal has NO oil groove, and rather the head has a groove machined into it....the bearing fits over the groove, and oil goes around the bearing and feeds the front journal at the top of the bearing only (no lower oil hole in the bearing).

Can't put a post-1980 OEM Opel camshaft into an earlier head without damage! Unless you machined the front journal with an oil groove that is...

Anyway, back to zephead69's problem. Probably a partial blockage of the front bearing journal. I've seen this a lot, there was about a 10-year run of US-made (Sealed Power/TRW) cam bearings with improperly located oil holes. On every engine I built with those bearings I had to manually redrill the oil passages. I got so used to it I almost forgot about it!

There are also a few other possibilities. One, the aforementioned aluminum oil plugs in the top of the head...they can pop out. Two, the timing cover castings can have some variation....I've seen one case where the oil passage that feeds the head was almost completely mis-aligned. Three, the gasket that goes between the head and the timing cover can be off a bit...I've seen this a lot too, it may block the oil passage by 50% or more.
I always 'blueprint' this area because it's a common malady. It often requires cutting the gasket to fit, and/or grinding the block and the timing cover to match the oilways up.

[hrcollinsjr]

I parked my daily driven GT years ago when it suddenly quit oiling to the head. I will admit I tried some miracle rebuild in a can product about a week prior to the problem. At the time I really didn't care because it was a low compression engine and I wanted to "improve" it. The wife just wanted it back like it was, so it is still sitting. At this point she doesn't much care what I do to it as long as I get it back on the road. Unfortunately when I start working on it again I'll have to go back through probably everything that was good at the time that it was parked because of my neglect and hard headedness.

Harold

[zephead69]

Thanks guys...I appreciate the help, as always. I'm going to talk to my mechanic about some of these issues and see what he may be thinking. I really don't want to believe that the passageway is blocked, it seemed that the guy who built it was more than careful for something like that to happen. I guess we will see where to take this and hope that not too much damage has already been done.